For many Americans, cellphones have become irreplaceable tools to manage their lives and stay connected to the outside world, their families and networks of friends online. But increasingly, by several measures, that does not mean talking on them very much.

For example, although almost 90 percent of households in the United States now have a cellphone, the growth in voice minutes used by consumers has stagnated, according to government and industry data. This is true even though more households each year are disconnecting their landlines in favor of cellphones.

Instead of talking on their cellphones, people are making use of all the extras that iPhones, BlackBerrys and other smartphones were also designed to do — browse the Web, listen to music, watch television, play games and send e-mail and text messages.

The number of text messages sent per user increased by nearly 50 percent nationwide last year, according to the CTIA, the wireless industry association. And for the first time in the United States, the amount of data in text, e-mail messages, streaming video, music and other services on mobile devices in 2009 surpassed the amount of voice data in cellphone calls, industry executives and analysts say.